N2H4 and NH3 as precursors for silicon nitride thin film growth

Abstract

The thermal decomposition of ammonia (NH3) and hydrazine (N2H4) on the Si(100) surface has been characterized using Auger electron spectroscopy (AES), temperature programmed desorption, and low energy electron diffraction (LEED). Successive cyclic dosing of the Si(100)-(2×1) [E. A. Wood, J. Appl. Phys. 35, 1306 (1964); H. H. Farrell, F. Stucki, J. Anderson, D. J. Frankel, G. J. Lapeyre, and M. Levinson, Phys. Rev. B 30, 721 (1984)] surface with the nitride precursor resulted in the formation of an amorphous nitride layer as indicated by LEED. Hydrazine nitrided the Si(100)-(2×1) surface much more rapidly than ammonia, as shown by a comparison of the AES nitridation curves for NH3 and N2H4. These nitridation curves have very different slopes and clearly have different functional forms. The marked difference in nitride formation rates during cyclic dosing and heating, along with the absence of NH3 desorption during N2H4 decomposition, suggest that NH3 and N2H4 may result in the formation of different types of nitride overlayer and/or have different thermal decomposition mechanisms.